Holders Brazil and their Group B rivals breathed life into the Copa America in two six-goal thrillers as they qualified for the quarter-finals with Venezuela and Paraguay on Wednesday.
Brazil won the group on goal difference from Venezuela, former whipping boys of South American soccer, with a 4-2 victory over Ecuador and will meet Paraguay in La Plata on Sunday.
Much-improved Venezuela, 1-0 up after five minutes but 3-1 down going into the 90th, struck twice for a 3-3 draw with Paraguay in Salta that put them in a last-eight meeting with Group A winners Chile in Mendoza.
Peru, with Paraguay one of the two best third-placed teams in the 12-nation competition, head to Cordoba to meet Group A winners Colombia in Saturday's quarter-finals, while hosts Argentina meet old rivals Uruguay in Santa Fe.
After a dearth of goals marred opening matches, Lionel Messi-led Argentina may have sparked the tournament into life with their 3-0 victory over Costa Rica on Monday, but Brazil's display served notice the champions were beginning to gel under coach Mano Menezes.
"Today's was Brazil's best match of the tournament so far," Menezes told a news conference after two changes -- Maicon at right back and Robinho in attack -- gave his team more punch.
However, Menezes remained wary of Paraguay's strengths after Brazil shared a 2-2 draw with coach Gerardo Martino's side four days ago in their previous group match.
"We know Paraguay's coach can put out a team that will be hard to beat but that's our path," Menezes said.
Young strikers Alexandre Pato and Neymar scored two goals apiece for Brazil, winners of four of the last five tournaments, while eliminated Ecuador contributed two fine equalisers from big forward Felipe Caicedo.
Typical of the traditional Brazilian virtues Menezes has sought to revive was their second goal facilitated by playmaker Paulo Henrique Ganso, who took a ball with his back to the net, turned and slotted it through for Neymar to shoot into the top corner.
Eliminated Ecuador's Colombian coach Reinaldo Rueda signed off by saying: "Given our hopes, this (tournament) was negative for Ecuador. Today we played better but it wasn't enough against effective rivals like Brazil."
Paraguay were guilty of failing to defend the two-goal lead they got four minutes from time when midfielder Cristian Riveros sent a glancing header inside the near post from a free kick from the right.
Striker Nicolas Fedor pulled one back in the final minute and three minutes into added time Grenddy Perozo equalised with a diving header at a corner.
"The team never lost their cool. We're a mentally strong team and we showed that today," Fedor told reporters.
Goalkeeper Renny Vega played a key part when he came up into the box for the last-ditch corner and his header into the middle was met by Perozo.
"They called me from the bench to go up. Thank God we did it," he said.